The present invention relates to a punching machine and more particularly, to such a punching machine, which is installed in the machine base of a roller shape forming machine in a metal working system and controlled to punch holes on a metal sheet material being delivered through the roller shape forming machine during operation of the roller shape forming machine.
In a metal working system, as shown in FIG. 1, metal sheet material 90 is fed to a hydraulic punch 91 and punched by the hydraulic punch 91 to have holes at desired locations, and then the punched metal sheet material 90 is carried by a material feeder 92 to a roller shape forming machine 93 and rammed into the desired shape. This metal working system is still not satisfactory in function because of the following drawbacks:                1. Because the processing speed of the hydraulic punch 91 is relatively slower and the feeding speed of the material feeder 92 is relatively faster, a sensor must be installed in between the hydraulic punch 91 and the material feeder 92 to control the operation of the roller shape forming machine 93 subject to the punching speed of the hydraulic punch 91. This operation procedure is complicated, lowering the manufacturing speed.        2. The hydraulic punch 91 and the material feeder 92 are heavy and expensive, requiring much floor space.        
The present invention has been accomplished under the circumstances in view. According to one aspect of the present invention, the punching machine is installed in the machine base of a roller shape forming machine in a metal working system and controlled to punch holes on a metal sheet material being delivered through the roller shape forming machine during operation of the roller shape forming machine. The punching action, i.e., the cycling of the closing and opening actions of the punch mold of the punching machine is set to match with the delivering speed of the metal sheet material in the roller shape forming machine so that the punching operation of the punching machine is continued during processing operation of the roller shape forming machine. According to another aspect of the present invention, the punch mold of the punching machine comprises an upper mold holder, which holds a number of upper punching dies, and a lower mold holder, which holds a number of bottom punching dies corresponding to the upper punching dies. The number of the upper punching dies and the bottom punching dies can be adjusted subject to the number of holes to be punched on the metal sheet material being delivered through the roller shape forming machine.